The present invention relates to a new and improved construction of starter or starting apparatus for a continuous casting plant or installation, especially for the casting of steel strands.
Generally speaking, the starter apparatus of the present development is of the type wherein a felxible dummy or starting bar provided with a dummy bar head for closing the opening of a continuous casting mold can be displaced by a drive into the arcuate or curved strand guiding arrangement or roller apron, and for the intermediate storage of the dummy bar such can be moved into a guide device which is pivotable in a substantially vertical plane.
During the continuous casting of steel strands the continuous casting mold is closed at its bottom end at the start of the casting operation by means of a dummy bar head which is arranged at a dummy or starting bar. This dummy bar head prevents the outflow of the liquid steel during the start of the casting operation. The steel solidifies at the dummy bar head which is provided with an undercut portion, so that the cast strand is securely connected with the dummy or starting bar. During the start of the continuous casting operation the dummy bar, which is transported by drive rolls through the strand guide arrangement or roller apron determines the withdrawal speed of the cast strand or casting. After the start of the casting operation the dummy bar head is released from the cast strand and the dummy bar is conveyed from the run-out roller table or bed to an intermediate storage.
According to a prior art continuous casting plant, as disclosed in U.S. Pat. No. 3,351,124, granted Nov. 7, 1967, there is pivotably mounted at the casting hall framework or girders a guide device serving as the intermediate storage for the dummy or starting bar. The free end of such guide device can be lowered by the action of a pressurised fluid medium cylinder arrangement up to the region of a transport or conveying plane of a run-out roller bed of the continuous casting plant. The dummy bar is pulled by a traction cable into the guide device for intermediately storing such dummy or starting bar. In order to start-up the continuous casting plant the dummy bar, following the outfeed of the cast strand upon the run-out or delivery roller bed, is lowered and conveyed by the driving unit or drive rolls through the roller apron until the dummy bar head closes the continuous casting mold. A great deal of time is needed between the pouring or teeming operations for inserting the dummy bar from the run-out roller bed through the entire strand guide arrangement or roller apron after the complete run-out of the cast strand.
It is already known to the art from U.S. Pat. No. 3,817,316, granted June 18, 1974 to introduce the dummy bar from above the casting platform through the mold opening into the strand guide arrangement or roller apron, in order to reduce the time losses resulting from the run-out of the end of the cast strand and the insertion of the dummy bar. Since this can be accomplished already during the run-out of the cast strand there is reduced, in this manner, the downtimes of the casting plant.
In German Pat. No. 2,221,187, granted Oct. 2, 1980, there is disclosed an apparatus for the insertion of the dummy bar from above through the mold opening into the strand guide arrangement. This apparatus comprises a carriage which can travel upon the casting platform and contains a dummy bar bed which can be pivoted into a vertical transfer position, and which is provided with a hook for the suspension of the dummy or starting bar as well as with a chain drive for the insertion of the dummy bar into the strand guide arrangement or roller apron. With this equipment the dummy bar is suspended at a crane hook and raised from the run-out roller table or bed to a location above the casting platform and transferred to the hook of the vertically disposed dummy bar bed. After the downward pivoting of the dummy bar bed it is possible, for instance, to exchange a dummy or starting bar head or to alter its format. Thereafter, the carriage is brought to the continuous casting mold and the dummy bar is lowered by means of the chain drive through the intermediary of an arcuate guide arrangement through the mold opening into the strand guide arrangement or roller apron. This starter apparatus is not advantageous for use with twin-pours, since the intermediate separation or partition wall of the mold hinders the insertion of the dummy bar from above.
With the known constructions of apparatus the accommodation of the dummy bar head to a new casting format or sectional shape can be accomplished within certain tolerances or limits by mounting or removing lateral adaptation or fitting elements. In the case of larger format changes, and equally when encountering wear of the dummy bar head, the latter must be exchanged with the aid of a crane. For such work there must be available during the standstill or downtimes operating personnel and a crane or the like.